
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>累加按钮，自加1</title>
<style>
body{text-align:center;}
input{font:12px arial;cursor:pointer;padding:0 10px;}
</style>
<script type="text/javascript">
window.onload = function ()
{
	var aBtn = document.getElementsByTagName("input")[0];
	var i = 0;
	
	aBtn.onclick = function ()
	{
		/* i++和++i在通过设置变量i之后，效果等同于i=0,sum=1,sum+=i; */
		aBtn.value = ++i;	
		alert(i)
	}	
}
</script>
</head>
<body>
<input type="button" value="0" />
</body>
</html>
